In one of our offices we have a Dell PowerVault 745N NAS device which acts as the main file server. Its running 32bit Windows 2003 Storage Server SP2 with 3GB RAM. The server holds around 60 users HOME folders, which are mapped via AD. The office clients are a mix of XP SP3, Vista and Windows 7. Occasionally the server will completely hang when transferring large files. When the hang happens the console becomes unresponsive with only the mouse active and blank wallpaper. Sometimes stopping the copy frees the server, sometimes not. The hanging can last around 20 minutes. During this time other servers also become unresponsive with blank wallpaper at the console. If you do manage to get onto another server the taskbar and run commands are unresponsive. This also transcends to the client computers sometimes with explorer crashing. I'm guessing this is due to the HOME folder mapping. Eventually the NAS server with free up and everything will be back to normal. The server is configured as follows: PERC 4/DC DATA 2 - 12 SCSI HDD - RAID5 SHADOWCOPY 2 SCSI HDD - RAID1 CERC SATA DATA 11 4 SATA HDD - RAID5 OS 4 SATA HDD - RAID5 All the drivers and firmware is up to date. I've been through all the diagnostics with Dell and the hardware has come up clean including full HDD tests on the arrays. The server has NOD32 installed as the AV, but the hanging happens when it is uninstalled. There are no errors in the event log when this happens and we don't have any errors logged on any of our ProCurve switches. DNS is fine on the domain and AD from what I can tell is running happily. There are no DFS or NFS shares setup either. All the shares are standard Windows. I've unchecked the allow the computer to turn off this device to save power box under Power Management on the NIC. "Set Link Speed and Duplex to Auto-negotiate 1000 " Increased Receive Descriptors buffer from 256 to 352 (reserves more CPU resource for handling data) I've run network traces using network monitor and have found the following: 417 8.078125 {SMB:192, NbtSS:25, TCP:24, IPv4:23} 192.168.2.244 192.168.5.35 SMB SMB:R; Nt Create Andx - NT Status: System - Error, Code = (52) STATUS_OBJECT_NAME_NOT_FOUND I've tried different cabling; NICs and switch ports all with the same result. Transferring files from other servers on the domain is fine. All I haven't done is run CHKDSK on the drives to look for any file system errors. On the Vista clients I have also run netsh interface tcp set global autotuning=disabled with no result. Could it be that the server has a faulty drive or that the I/O is too much for it to handle? Any ideas why would the hang cause issues with the other servers on the LAN? Many Thanks.